In this video segment adapted from 'Need to Know,' learn about health concerns regarding exposure to chemicals used in natural gas drilling. An animation shows how the process of hydraulic fracturing-fracking-is used to extract natural gas. A reporter explains how the process may be polluting water resources with hazardous chemicals. Hear about health problems among people whose only common connection is proximity to gas drilling sites. In addition, learn about the challenges of investigating the possible link between the contaminants and illness because the gas industry is not required to disclose which chemicals they use in fracking fluids. [5:44]

In this video segment from 'Greater Boston,' Liz Lombard describes her struggle with a painful, progressive autoimmune disease called scleroderma. Scleroderma is rare, so Lombard was surprised to learn that other people in her South Boston neighborhood also had the disease. Health officials explain that there is a genetic predisposition to scleroderma, and there may be environmental factors involved as well. However, officials don't know whether this particular cluster is a result of environmental hazards or simply a coincidence. Includes background essay and discussion questions. [3:22]

In this video segment adapted from 'Need to Know,' meet a fisherman who became a cleanup worker on the 2010 BP oil spill and then developed health problems. Learn about concern over the health and safety of cleanup workers because of the amount of oil and dispersant they were exposed to and the duration of exposure. Hear about how hazardous hydrocarbons reached the surface of the water and got into the air. Learn about common symptoms associated with exposure to crude oil and chemical dispersant; in addition, hear concerns about the chemicals ending up in the food chain and the unknown long-term health risks that this may pose. Includes background essay and discussion questions. [3:32]

In this video segment adapted from Lead Awareness for Parents by the Coalition to Prevent Lead Poisoning, learn about potential effects of lead exposure and how to reduce impacts. A physician describes ways that children are commonly exposed to lead and how elevated blood lead levels can affect their health. Hear about methods to reduce the incidence and severity of lead poisoning, including routine blood testing, home inspections, and proper nutrition. Includes background essay and discussion questions. [2:24]

Meet Erica, a high school student from Oxnard, California, in this video excerpt from Earth Island Institute. Learn how she fought the construction of a proposed liquefied natural gas facility near her low-income, Latino neighborhood. Hear from a member of the Sierra Club who describes the proposed facility, and hear how Erica educated people about the potential environmental impacts and how to get involved to stop the project. Includes background essay and discussion questions. [4:42]

New York student Shadia Wood tells how she became an environmental activist in this video adapted from Earth Island Institute's New Leaders Initiative. Wood lives near several toxic waste sites and was concerned to learn that the New York Superfund - the money set aside for cleaning such sites in her state - had gone bankrupt. Working with other students and environmental groups, Wood lobbied the New York legislature for eight years until the Superfund program was refinanced. Environmentalist Laura Haight says that this law was the most important environmental law passed in New York State in a decade. Includes background essay and discussion questions. [3:57]

Meet Marisol, a high school student from Little Village in Chicago, and learn how she found out about the toxins produced by the local coal-burning power plant in her community in this video adapted from Earth Island Institute. Discover some of the health risks associated with such pollution, and observe how Marisol helped create OurMap of Environmental Justice, an interactive online map that includes videos, facts, and descriptions of toxic pollutants in the community. Includes background essay and discussion questions. [3:13]

In this Building Block video from Frontline: Nuclear Reaction, the four cooling towers at the Three Mile Island nuclear power plant dot the horizon at sunrise. Smoke billows from the two towers on the left. The Susquehanna River lies in the foreground. [0:26]

A detailed outline containing a large amount of material on wind erosion, describing wind transport mechanisms, and wind landform formation.

Explore plant and animal cells with this interactive site. Explanations are provided for each cell organelle.

An introduction to the structure of two different types of cells: eukaryotic and prokaryotic cells. [2:14]

In this adapted video segment, ZOOM guest Tommy takes us on a tour of the Florida Everglades. He describes what makes a wetland biome unique, including the soil, precipitation, and biodiversity. [2:53]

These pages are part of a site called "Evolution," that accompanies a textbook by the same name. Mark Ridley is the author, and in this section he discusses the evidence for evolution.

An overview of the different types of evidence that support evolution, including homologous and analogous features and vestigial structures. [12:59]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

These pages are part of a site called Evolution that accompanies a textbook by the same name. Mark Ridley is the author. These pages offer an explanation of speciation using reproductive isolation and differences in phenotype.

Observe and annotate various images of weather phenomena in this interactive drawing tool. Students can use the images in this tool to observe weather conditions and document evidence of weather that happened earlier in the day. Teacher and student support materials are provided.

Explore the evidence of evolution with this interactive worksheet based off of NOVA's Evolution Lab. This resource is designed to be completed while playing through the Evolution Lab game and contains multiple choice and free response questions and covers Mission 1 of the Evolution Lab game with embedded videos. Mission 1 introduces students to natural selection and how to interpret and create phylogenetic trees. Below are links to the remaining missions of the Evolution Lab.

An introduction to Darwin's theory of evolution with hyperlinks to other topics on evolution, including a timeline of evolutionary thought.

Zoologist Dan-Erik Nilsson demonstrates how the complex human eye could have evolved from simple light-sensitive cells. From a PBS show called "Evolution: Darwin's Dangerous Idea." Includes background reading material and discussion questions. [4:08]